Taxane prodrugs

ABSTRACT

Taxane prodrugs comprise a taxane joined by a hydrolyzable bond to one or more oligomers that comprise a polyethylene glycol moiety. The oligomer preferably further comprises a salt-forming moiety.

RELATED APPLICATION

[0001] This application is a continuation-in-part of commonly owned,co-pending application Ser. No. 09/476,974 of Ekwuribe et al., filedDec. 31, 1999, the disclosure of which is incorporated by referenceherein in its entirety.

1. BACKGROUND OF THE INVENTION

[0002] 1.1 Field of the Invention

[0003] The present invention relates generally to taxane-oligomerconjugates and to methods for making and using such conjugates. Thetaxane-oligomer conjugates of the invention operate as prodrugs,hydrolyzing under normal physiological conditions to providetherapeutically active taxanes, such as paclitaxel or docetaxel. Thetaxane-oligomer conjugates exhibit improved solubility characteristics,improved oral bioavailability, and an improved pharmacokinetic profile.The present invention also relates to pharmaceutical compositionscomprising these taxane-oligomer conjugates and to methods of making andusing such taxane-oligomer conjugates and pharmaceutical compositions.

[0004] 1.2 Description of the Prior Art

[0005] Paclitaxel (Taxol) is a natural diterpene product isolated fromthe pacific yew tree (Taxus brevifolia). Wani et al. first isolatedpaclitaxel in 1971 by chemical and X-ray crystallographic methods.Paclitaxel is a complex diterpene having a taxane ring with a 4-memberedoxetane ring and an ester side chain at position C-13. The complexstructure of paclitaxel is as follows:

[0006] Paclitaxel has been approved for clinical use in the treatment ofrefractory ovarian cancer in the United States. (Markman 1991; McGuireet al. 1989). Paclitaxel has also been approved for treatment of breastcancer. (Holmes et al. 1991) Additionally, paclitaxel is a candidate fortreatment of neoplasms of the skin (Einzig et al.) and head and neckcarcinomas (Forastire et al. 1990). Paclitaxel is also useful for thetreatment of polycystic kidney disease (Woo et al. 1994), lung cancerand malaria.

[0007] Paclitaxel mediates its anti-cancer effects by lowering thecritical concentration of tubulin necessary for microtubule formation.Microtubules are polymers of tubulin in dynamic equilibrium with tubulinheterodimers that are composed of α and β protein subunits. Paclitaxelshifts the equilibrium towards microtubule assembly. Paclitaxel-inducedmicrotubules are excessively stable, thereby inhibiting dynamicreorganization of the microtubule network, and resulting in microtubulebundles that form during all phases of the cell cycle and numerousabnormal mitotic asters that are not associated with centrioles.

[0008] Paclitaxel entered Phase I clinical trials in 1983, butimmediately encountered formulation difficulties due to its aqueousinsolubility. This difficulty was partially overcome by formulatingPaclitaxel as an emulsion with Cremophor EL®. However, since paclitaxelmust be given at relatively high dosages, large amounts of Cremophor EL®are required. When administered intravenously, such formulations canproduce vasodilatation, labored breathing, lethargy, hypertension anddeath in dogs, and are also believed to be responsible for theallergic-type reactions observed during paclitaxel administration inhumans. Accordingly, there is a need in the art for a means foradministering paclitaxel which increases its water solubility andthereby avoids the need for formulating paclitaxel with potentiallyallergenic emulsion reagents.

[0009] Efforts to overcome the allergy problems of formulated paclitaxelhave thus far been directed at lengthening the infusion time andpremedicating patents with immunosuppressive agents, such asglucocorticoids and also with antihistamines. These agents have theirown set of side effects and are an added cost to the already expensivecost of cancer treatment. Furthermore, while such agents have been shownto reduce the incidence and severity of hypersensitivity reactions, theyare not fully protective. (Rowinsky et al. 1992). Accordingly, there isa need in the art for means for administering paclitaxel which avoidslengthened infusion times and the allergic reactions associated withemulsion reagents and thereby also avoids the need for such adjunctivetreatment.

[0010] Several groups have investigated the synthesis of prodrug formsof paclitaxel. (Taylor 1994); (Kingston, D. G. 1991). Prodrugs areinactive or partially inactive chemical derivatives of drugs that aremetabolized to yield the pharmacologically active drug. Studies havebeen directed toward synthesizing paclitaxel analogs where the 2′ and/or7-position is derivatized with groups that enhance water solubility.These efforts have yielded prodrug compounds that are more water-solublethan the parent compound while displaying the cytotoxic properties ofpaclitaxel upon activation. For example, increased water-solubility hasbeen achieved by derivatizing paclitaxel with high molecular weightpolyethylene glycol (PEG) polymers. (See Greenwald, et al. 1996;Greenwald et al. 1995). However, while these derivatized paclitaxelcompounds have increased solubility, they also result in a correspondingdecrease in drug load, due to the high molecular weight PEG necessary toachieve adequate solubility. Accordingly, there is a need in the art fortaxane prodrugs which improve paclitaxel solubility without drasticallyincreasing the molecular weight of the paclitaxel compound.

[0011] Efficient utilization of prodrugs, especially taxane prodrugs,requires that the properties of the prodrug must be adequately balancedto achieve a useful pharmacokinetic profile. In one aspect, it isdesirable for the prodrug to be hydrophilic in order to enhance theability to formulate the prodrug. On the other hand, the prodrug must beappropriately hydrophobic to permit interaction of the prodrug withbiological membranes. There is therefore a need in the art for taxaneprodrugs that accommodate the foregoing disparate requirements foruseful therapeutic agents.

2. SUMMARY OF THE INVENTION

[0012] The present inventors have surprisingly and unexpectedlydiscovered taxane-oligomer compounds and salts of such compounds(collectively referred to herein as “taxane prodrugs”) thatsignificantly increase the water-solubility of taxane drugs withoutdrastically increasing their molecular weight. The taxane prodrugsdescribed herein eliminate the need for microemulsion formulation usingCremophor EL®.

[0013] Embodiments according to the present invention provide a taxaneprodrug comprising a taxane joined by a hydrolyzable bond to an oligomerhaving the following formula:

[0014] wherein n is from 1 to 12, m is from 1 to 25, p is from 2 to 12,X⁺ is a positive ion and Z⁻ is a negative ion.

[0015] In other embodiments of the present invention, the taxane ispaclitaxel or a paclitaxel analog which retains some or all of thetherapeutic activity of paclitaxel. Taxane may also be docetaxel.

[0016] The taxane prodrug may be derivatized by as many oligomers asthere are sites on the taxane for attachment of such oligomers. Forexample, paclitaxel has 3 attachment sites (hydroxyl groups) and cantherefore be derivatized by 1, 2 or 3 of the oligomers. Similarly,docetaxel paclitaxel has 4 attachment sites (hydroxyl groups) and cantherefore be derivatized by 1, 2, 3 or 4 of the oligomers.

[0017] In another aspect, the taxane prodrugs can be delivered via oraladministration to provide a therapeutically effective dose of the taxaneto the bloodstream. Furthermore, the orally delivered prodrugs canprovide a therapeutically effective dose of the taxane to the targetorgan or tissue.

[0018] Embodiments of the present invention also provide pharmaceuticalcompositions comprising the taxane prodrugs of the invention inassociation with a pharmaceutically acceptable carrier. Suchpharmaceutical compositions may be formulated so as to be suitable fororal administration, and may be in a dosage form selected from the groupconsisting of: tablets, capsules, caplets, gelcaps, pills, liquidsolutions, suspensions or elixirs, powders, lozenges, micronizedparticles and osmotic delivery systems. Methods for treating a mammaliansubject having a paclitaxel-responsive disease condition are alsoprovided. The mammalian subject is preferably a human.

[0019] In one aspect of the methods of treatment, the taxane prodrug isdelivered via an oral route of administration to provide atherapeutically effective dose of the taxane into the bloodstream. Inanother aspect, the taxane prodrug is delivered via a parenteral routeof administration, providing a therapeutically effective dose of thetaxane to target organs and/or tissues. In yet another aspect, thetaxane prodrug is delivered via an oral route of administration,providing a therapeutically effective dose of the taxane to targetorgans and/or tissues. Furthermore, the taxane prodrug may beadministered in association with a pharmaceutically acceptable carrier.

[0020] In a further aspect, the taxane-responsive disease conditiontreated according to the therapeutic methods of the invention isselected from the group consisting of benign and malignant neoplasms,and may include hepatocellular carcinoma, urogenital carcinoma, livermetastases, gastrointestinal cancers, lymphoma, leukemia, melanoma,Kaposi's sarcoma, and cancers of the pancreas, kidney, cervix, breast,ovary, brain, and prostate. In one aspect, the disease conditioncomprises ovarian cancer and the taxane prodrug is administeredoptionally with cisplatin, either simultaneously or sequentially. Inanother aspect, the disease condition comprises breast cancer and thetaxane prodrug is administered optionally with doxorubicin, eithersimultaneously or sequentially.

[0021] 2. Definitions

[0022] As used herein the term “PEG” refers to straight or branchedpolyethylene glycol oligomer and monomers and also includes polyethyleneglycol oligomers that have been modified to include groups which do noteliminate the amphiphilic properties of such oligomer, e.g. withoutlimitation, alkyl, lower alkyl, aryl, amino-alkyl and amino-aryl. Theterm “PEG subunit” refers to a single polyethylene glycol unit, i.e.,—(CH₂CH₂O)—.

[0023] As used herein, the term “lower alkyl” refers to a straight orbranched chain hydrocarbon having from one to 8 carbon atoms.

[0024] As used herein, terms such as “non-hydrolyzable” and phrases suchas “not hydrolyzable” are used to refer to bonds which cannot behydrolyzed under normal physiological conditions, as well as bonds whichare not rapidly hydrolyzed under normal physiological conditions such ascarbamate and amide bonds. The term “hydrolyzable” refers to bonds whichare hydrolyzed under physiological conditions. In a preferred aspect ofthe invention, 50% of the taxane prodrug is hydrolyzed in a normalpopulation within 4 hours after intravenous administration.

[0025] A “therapeutically effective amount” is an amount necessary toprevent, delay or reduce the severity of the onset of disease, or anamount necessary to arrest or reduce the severity of an ongoing disease,and also includes an amount necessary to enhance normal physiologicalfunctioning.

[0026] As used herein, a “pharmaceutically acceptable” component (suchas a salt, carrier, excipient or diluent) of a formulation according tothe present invention is a component which (1) is compatible with theother ingredients of the formulation in that it can be combined with thetaxane prodrugs of the present invention without eliminating thebiological activity of the taxane prodrugs; and (2) is suitable for usewith an animal (e.g., a human) without undue adverse side effects, suchas toxicity, irritation, and allergic response. Side effects are “undue”when their risk outweighs the benefit provided by the pharmaceuticalcomposition. Examples of pharmaceutically acceptable components include,without limitation, standard pharmaceutical carriers, such as phosphatebuffered saline solutions, water, emulsions such as oil/water emulsions,microemulsions, and various types of wetting agents.

[0027] As used herein, the term “taxane” is used to refer to a class ofcompounds having a basic three ring structure which includes rings A, Band C of paclitaxel:

[0028] including, without limitation, paclitaxel and paclitaxel analogswhich retain some or all of the anti-cancer activity of paclitaxel.

3. BRIEF DESCRIPTION OF THE DRAWINGS

[0029]FIG. 1 shows the conversion of acetate (Compound 4) (see Examplesbelow) to paclitaxel over the course of 26 days at room temperature,where the acetate (Compound 4) was dissolved in wet acetonitrile. FIG. 1shows that acetate (Compound 4) smoothly converted quantitatively intopaclitaxel with no significant side product formation, as observed byanalytical HPLC analysis.

[0030]FIG. 2 shows in vitro hydrolysis of acetate (Compound 4) inheparinized rat plasma and demonstrates that most of the taxane prodrugrapidly hydrolyzes within two hours to provide free paclitaxel.

[0031]FIG. 3 shows percent growth of NIH:OVCAR-3 cells treated withcompounds of the present invention in comparison with paclitaxel.

[0032]FIG. 4 shows caspase-3 activation by NIH:OVCAR-3 cells stimulatedwith compounds of the present invention in comparison with paclitaxel.

4. DETAILED DESCRIPTION OF THE INVENTION

[0033] The ensuing detailed description is divided into sections forease of reference only. Subject headings are not intended to limit thescope of the invention.

[0034] 4.1 Taxane-Oligomer Prodrugs

[0035] The present invention provides taxane-oligomer prodrugs (alsoreferred to herein as “taxane prodrugs”). The taxane prodrugs of thepresent invention generally comprise a taxane component and an oligomercomponent. The taxane prodrugs are generally useful in facilitating theformulation of taxanes in a hydrophilic formulation, the oral deliveryof taxanes, and the delivery of taxanes to target organs and tissues.

[0036] 4.1.1 Taxanes

[0037] Preferred taxanes are those having the constituents known in theart to be required for enhancement of microtubule formation, e.g.,paclitaxel and docetaxel. The structures of paclitaxel and docetaxel areknown in the art; however, for ease of reference, the structural formulaof paclitaxel is set forth in Figure in Section 1.2 above, and thestructural formula for docetaxel is as follows:

[0038] In a preferred mode, the taxane of the taxane prodrug is apaclitaxel analog. Many analogs of paclitaxel are known in the art whichdisplay more or less anti-cancer activity than paclitaxel itself. Thepresent invention contemplates the use of any paclitaxel analog thatdoes not have completely diminished anti-cancer activity.

[0039] In one class of analogs, the side chain N-benzoyl group isreplaced with other acyl groups. One such analog, docetaxel (Taxotere®),has an N-t-butoxycarbonyl group in place of the N-benzoyl group ofpaclitaxel and also lacks the 10-acetate group. Docetaxel is known to beabout five times as active as paclitaxel against paclitaxel-resistantcells and is currently in clinical use in both France and the U.S.A.

[0040] It is also known that reduction of the C-9 carbonyl group to anα-OH group causes a slight increase in tubulin-assembly activity.Additionally, it is known that a rearrangement product with acyclopropane ring bridging the seven and eight-position is almost ascytotoxic as paclitaxel.

[0041] Further suitable taxanes for use in the taxane prodrugs of thepresent invention are paclitaxel derivatives having structuralvariations along the “northern perimeter” portion of the paclitaxelmolecule. The “northern perimeter” comprises carbons 6-12, with oxygenIs functions at C-7, C-9 and C-10. Many such derivatives are known inthe art, and it is known that such derivatives exhibit biologicalactivity that is comparable to the bioactivity of paclitaxel. Thus, forexample, it is known acylation of the C-7 hydroxyl group, or itsreplacement with hydrogen, does not significantly reduce the activity ofpaclitaxel. Additionally, replacement of the 10-acetoxy group withhydrogen causes only a small reduction in activity.

[0042] It has been noted that m-substituted benzoyl derivatives are moreactive than their p-substituted analogs, and are often more active thanpaclitaxel itself.

[0043] Another paclitaxel analog suitable for use in the taxane prodrugsof the present invention is A-nor-paclitaxel. This analog hastubulin-assembly activity that is only three times less than that ofpaclitaxel. A-nor-paclitaxel and paclitaxel have very similar molecularshapes, which may explain their similar tubulin-assembly activities.

[0044] 4.1.2 Polymers/Oligomers

[0045] The PEG polymers/oligomers of the taxane prodrugs of the presentinvention may be straight or branched. Preferred oligomers have from 2to 25 PEG units, more preferably from 2 to 20 PEG units, still morepreferably from 2 to 15 PEG units. Ideally, the oligomer has from 2 to10 PEG units, i.e., 2, 3, 4, 5, 6, 7, 8, 9 or 10 PEG units. In anotheraspect, the oligomer has a molecular weight which is not greater than1000.

[0046] In a preferred mode, the PEG polymers/oligomers have the formula:

—(CH₂CH₂O)_(x)—CH₃  (Formula 1)

[0047] wherein X=2-25.

[0048] In a more preferred mode, X is from 2-20, still more preferablyfrom 2-15, and most preferably from 2-10. Ideally, X is 2, 3, 4, 5, 6,7, 8, 9 or 10.

[0049] Preferred oligomers are selected from the group consisting of:

[0050] wherein n is from 1 to 7, m is from 2 to 25, and R is a loweralkyl preferably selected from the group consisting of hydrogen, methyl,ethyl, propyl, isopropyl and t-butyl;

[0051] wherein n is from 1 to 6, p is from 2 to 8, m is from 2 to 25,and R is a lower alkyl, preferably selected from the group consisting ofhydrogen, methyl, ethyl, propyl, isopropyl and t-butyl;

[0052] wherein n is from 1 to 6, m and r are each independently from 2to 25, and R is a lower alkyl, preferably selected from the groupconsisting of hydrogen, methyl, ethyl, propyl, isopropyl and t-butyl;

[0053] wherein n is from 1 to 6, p is from 2 to 8 and m is from 2 to 25and R is a lower alkyl, preferably selected from the group consisting ofhydrogen, methyl, ethyl, propyl, isopropyl and t-butyl;

[0054] wherein n is from 1 to 6, p is from 2 to 8, m is from 2 to 25, X⁻is a negative ion, preferably selected from the group consisting ofchloro, bromo, iodo, phosphate, acetate, carbonate, sulfate, tosylateand mesylate, and R is a lower alkyl, preferably selected from the groupconsisting of hydrogen, methyl, ethyl, propyl, isopropyl and t-butyl;

[0055] wherein n is from 1 to 6, p is from 2 to 8, m is from 2 to 25,and R¹ and R² are each independently a lower alkyl, preferably selectedfrom the group consisting of methyl, ethyl, propyl, isopropyl, andt-butyl;

[0056] wherein n is from 1 to 6, p is from 2 to 8 and m is from 2 to 25;

[0057] wherein n and p are each independently from 1 to 6, m is from 2to 25 and X⁺ is a positive ion, preferably selected from the groupconsisting of hydrogen, sodium, potassium, calcium, lithium and ammoniumsalts;

[0058] wherein n is from 1 to 5, m is from 2 to 25, X⁻ is a negativeion, preferably selected from the group consisting of: chloro, bromo,iodo, phosphate, acetate, carbonate, sulfate and mesylate, and whereinR¹ and R² are each independently lower alkyl and are preferablyindependently selected from the group consisting of hydrogen, methyl,ethyl propyl, isopropyl and t-butyl;

[0059] wherein n is from 1 to 6, m is from 2 to 25 and X⁻ is a negativeion, preferably selected from the group consisting of: chloro, bromo,iodo, phosphate, acetate, carbonate, sulfate, and mesylate; and

[0060] wherein n is from 1 to 12, m is from 1 to 25, p is from 2 to 12,X⁺ is a positive ion and Z⁻ is a negative ion. Preferably, n is from 2to 8, and more preferably n is from 2 to 4. Preferably, p is from 2 to8, and, more preferably, p is from 2 to 4. X⁺ is preferably selectedfrom the group consisting of NH₃ ⁺ and trisubsitituted sulfur, namelysulfur substituted with one or more R′ and R″ where R′ and R″ each ismethyl, ethyl, propyl and butyl. For example X⁺Z⁻ is

[0061] Z⁻ is preferably selected from the group consisting of chloroanion, bromo anion, iodo anion, phosphate anion, acetate anion,trifluoracetate anion, carbonate anion, sulfate anion, and mesylateanion.

[0062] In any of the foregoing Formulae 1-12, the total number of PEGunits is preferably from 2 to 25, more preferably from 2-20, still morepreferably from 2-15, most preferably from 2-10. Ideally, the totalnumber of PEG units is 2, 3, 4, 5, 6, 7, 8, 9 or 10. In formulae, suchas Formula 4, which contain two PEG polymer segments, the preferrednumber of PEG units set forth in this paragraph may be containedcompletely in either of the two PEG polymer segments or may bedistributed between the two PEG polymer segments.

[0063] The oligomer/polymer may also comprise one or more salt formingmoieties. Preferred salt forming moieties are ammonium and carboxylate.Suitable salts also include any pharmaceutically acceptableacid-addition salts for oligomers/polymers having a basic amino groupand pharmaceutically acceptable salts derived from pharmaceuticallyacceptable bases for oligomers/polymers having, e.g., a free carboxygroup. Pharmaceutically acceptable salts of the acid may be prepared bytreating the free acid with an appropriate base. Pharmaceuticallyacceptable base salts include, for example, alkali metal salts such assodium or potassium, alkaline earth metal salts such as sodium orpotassium, alkaline earth metal salts such as calcium or magnesium, andammonium or alkyl ammonium salts.

[0064] 4.2 Methods for Producing the Paclitaxel-PEG Conjugates

[0065] Paclitaxel is commercially available and can be isolated bymethods known in the art from the bark of Taxus brevifolia. Paclitaxelcan also be isolated from the leaves (or needles) of various Taxusspecies in yields comparable to the yield from Taxus brevifolia bark.U.S. Pat. No. 5,019,504 describes tissue-culture methods for producingpaclitaxel. It is also known that paclitaxel is produced by the fungusTaxomyces andreanae.

[0066] Additionally, paclitaxel can be prepared by known syntheticmethods, for example, as reported by Holton et al., J. Am. Chem. Soc.116:1597-1598 (1994); Holton et al., J. Am. Chem. Soc. 116:1599-1600(1994); and Nicolaou et al., Nature 367:630-634 (1994).

[0067] In the ensuing examples, the n, p, m, R, and R¹ and R² symbolsare as described above in general Formulae 1-12.

[0068] 4.2.1 Formula 1

[0069] The polymers of Formula 1 are commercially available and/or arereadily synthesized by one of skill in the art without undueexperimentation.

[0070] 4.2.2 Formula 2

[0071] In the synthesis of the oligomers of Formula 2:

[0072] wherein n is from 1 to 7, m is from 2 to 25, and R is a loweralkyl, it is desirable to start with an ester of a fatty acid having aterminal carbon which bears a primary amino moiety. Such compounds arecommercially available. The amino ester in an inert solvent is treatedwith a solution of monomethoxy polyethylene glycol of appropriatemolecular weight bearing an aldehyde terminal carbon, followed by theaddition of a solution of sodium borohydride. The product is purifiedafter solvent extraction by column chromatography.

[0073] wherein n and m are as previously defined.

[0074] Sometimes it is desirable to alkylate the secondary amine moietyto form a desired oligomer bearing a tertiary amine. A solution of theoligomer in an inert solvent is treated with one equivalent of alkylhalide. The product is purified after solvent extraction by columnchromatography.

[0075] The ester is converted to an acid by treating it in an inertsolvent with a dilute solution of sodium hydroxide at room temperature.The free acid is purified after solvent extraction by columnchromatography. The acid is coupled to the drug after in situactivation.

[0076] The drug in these examples can be, for example, paclitaxel ordocetaxel.

[0077] It is sometimes desirable to synthesize the drug-oligomer bystarting with the therapeutic compound derivatized as an ester of fattyacid having a terminal carbon which bears a halide and an appropriatemonomethoxy-polyethylene glycol with a terminal carbon bearing a primaryamino moiety. The polyethylene glycol reagent is dissolved in an inertsolvent at room temperature. An equivalent amount of the drug-halide isdissolved in an inert solvent and added slowly to the solution ofpolyethylene glycol. The product is purified after solvent extractionusing column chromatography.

[0078] The ester is hydrolyzed with a dilute solution of sodiumhydroxide as in the previous procedure and coupled to the drug (e.g.,paclitaxel or docetaxel) after in situ activation as in the previousexample.

[0079] 4.2.3 Formula 3

[0080] In the synthesis of the oligomer of Formula 3:

[0081] wherein n is from 1 to 6, p is from 2 to 8, m is from 2 to 25,and R is a lower alkyl, it is desirable to start with a half-ester of adicarboxylic acid of an aliphatic compound and an amino-containingpolyethylene. In the synthesis of the amino-containing polyethylene, anappropriate molecular weight monomethyl polyethylene glycol having analdehyde moiety at the terminal end is treated in an inert solvent withan aliphatic compound bearing amino moieties at the two terminalcarbons. One amino moiety is protected with tert-butoxycarbonyl whilethe free amine reacts with the aldehyde moiety The product is purifiedafter solvent extraction column chromatography. The product isdeprotected by treating in an inert solvent with trifluoroacetic acid,neutralizing the acid and purifying after solvent extraction usingcolumn chromatography.

[0082] The half ester in an inert solvent is treated with a solution ofthe amino-derivatized polyethylene glycol at room temperature after anin situ activation of the acid. The product is purified by columnchromatography after solvent extraction. The imino moiety is reduced bytreating with a solution of sodium borohydride and purified as in theprevious procedure.

[0083] It is sometimes desirable to alkylate the secondary amine. Toachieve this end, the oligomer is dissolved in an inert solvent andtreated with a solution of an alkyl halide in an inert solvent.

[0084] The ester is hydrolyzed, activated in situ, and coupled to thetherapeutic compound (e.g., paclitaxel or docetaxel).

[0085] where D indicates the drug component of the drug-amphiphileconjugate. The amphiphilic drug conjugate is converted to a salt form toimprove aqueous solubility as necessary using a pharmaceuticallyacceptable acid.

[0086] 4.2.4 Formula 4

[0087] The procedure for the synthesis of the oligomer of Formula 4:

[0088] wherein n is from 1 to 6, m and r are each independently from 2to 25, and R is a lower alkyl, is the same as for the oligomer ofFormula 3 with the exception that the aliphatic diamino moieties arereplaced with polyethylene glycol diamine.

[0089] 4.2.5 Formula 5

[0090] In the synthesis of a prodrug comprising the oligomer of Formula5:

[0091] wherein n is from 1 to 6, p is from 2 to 8 and m is from 2 to 25and R is a lower alkyl, the drug bearing a hydroxyl moiety is treated inan inert solvent with an aliphatic acid anhydride to form a half ester.The half-ester is dissolved in an inert solvent, activated and treatedwith one equivalent of a polyethylene glycol of appropriate molecularweight, in which the terminal hydroxyl moieties are replaced with aminomoieties.

[0092] where all substituent groups (e.g., n, m and p) are as previouslydefined.

[0093] 4.2.6 Formula 6

[0094] The oligomer of Formula 6:

[0095] wherein n is from 1 to 6, p is from 2 to 8, m is from 2 to 25, X⁻is a negative ion, is prepared by treating the compound represented byFormula 5 with a pharmaceutically acceptable acid to obtain theappropriate salt. The salt increases the water-solubility of theamphiphilic drug conjugate.

[0096] 4.2.7 Formula 7

[0097] The synthesis of the oligomer of Formula 7:

[0098] wherein n is from 1 to 6, p is from 2 to 8, m is from 2 to 25,and R¹ and R² are each independently a lower alkyl, is analogous to thesynthesis of the oligomer of Formula 5, with the exception that theend-terminal amino moiety is alkylated with the halide of a short chainalkyl group such as methyl, ethyl, propyl, isopropyl or t-butyl beforereacting to the half-ester of the drug.

[0099] where n, m and R are as previously defined.

[0100] 4.2.8 Formula 8

[0101] In the synthesis of the oligomer of Formula 8:

[0102] wherein n is from 1 to 6, p is from 2 to 8 and m is from 2 to 25,the half-ester of the aliphatic dicarboxylic acid is treated in an inertsolvent with polyethylene glycol that has already been derivatized withamino moieties, after in situ activation.

[0103] The amino-derivatized polyethylene glycol is prepared from anN-protected polyethylene glycol amino acid

[0104] The primary amino moiety is deprotected with trifluoroacetic acidand basified before treating with the half-ester.

[0105] 4.2.9 Formula 9

[0106] In the synthesis of the oligomer of Formula 9:

[0107] wherein n and p are each independently from 1 to 6, m is from 2to 25 and X⁺ is a positive ion, the starting acid is commerciallyavailable. It is sometimes desirable to prepare the diacid. To achievethis end, the appropriate modified polyethylene glycol oligomer istreated in an inert solvent with sodium hydride and an ester of a fattyacid bearing a halide moiety at the terminal carbon. The carboxylic aciddiester is hydrolyzed in a dilute solution of sodium hydroxide andcoupled to the drug moiety after in situ activation. The desired productis separated and purified by column chromatography.

[0108] where n, m and p are as previously defined.

[0109] 4.2.10 Formula 10

[0110] The synthesis of the oligomer of Formula 10:

[0111] wherein n is from 1 to 5, m is from 2 to 25, X⁻ is a negativeion, and wherein R¹ and R² are each independently lower alkyl, isanalogous to the synthesis of the oligomer of Formula 2, with theexception that the amino moiety is quaternized with short-chainaliphatic moieties. It is noted that the methoxy moiety can includeother short chain (1 to 6 carbons) aliphatic moieties.

[0112] 4.2.11 Formula 11

[0113] In the synthesis of the oligomers of Formula 11:

[0114] wherein n is from 1 to 6, m is from 2 to 25 and X⁻ is a negativeion, a 2-fluoro- or 4-fluoro-pyridine is treated in an inert solventwith a monomethoxypolyethylene glycol having a terminal carbon bearing ahalide, tosylate or mesylate ion. This pyridinium derivative isprecipitated and triturated with an appropriate solvent and dried. Thesalt in an inert solvent is treated with drug, such as paclitaxel ordocetaxel, in the presence of a quaternary-salt compound forming base,to yield a polyethylene glycol pyridinium derivative.

[0115] 4.2.12 Formula 12

[0116] Procedures for preparing the oligomers of Formula 12 aredescribed in the Examples of Section 5 below.

[0117] 4.2.13 Attachment of PEG Polymers/Oligomers to Taxane Parent

[0118] The oligomers are suitably attached to the taxane parent at anyof the hydroxyl substituents of the taxane parent. Where the taxaneparent is paclitaxel, docetaxel, or an analog thereof, the oligomers arepreferably attached at one or more of the following positions: the C-2′hydroxyl group; the C-7 hydroxyl group; and the C-1 hydroxyl group. In apreferred mode, only one oligomer is present, and the oligomer isattached at the C-2′ hydroxyl group. It will be appreciated by those ofskill in the art that a solution of taxane prodrugs according to thepresent invention where the taxane is paclitaxel, docetaxel or the likemay comprise a mixture of mono-, di-, and/or tri-substituted taxaneprodrugs.

[0119] The oligomers/polymers of the present invention can be attachedto the taxane compound to provide the taxane prodrugs of the inventionaccording to the following general synthetic procedure. The taxanecompound is dissolved in a substantially dry organic solvent, e.g.,chloroform. Pyridine or another quaternary-compound forming agent isadded to the foregoing mixture. Activated oligomer/polymer is addeddropwise and the mixture is stirred for 3-5 hours. Then reaction mixtureis washed with 1% H₂SO₄ and deionized water, dried over MgSO₄ andconcentrated. The residue is chromatographed on silica gel column, usingfor example, chloroform-methanol (90%-10%) as developing agent. Thefractions containing the desired prodrugs are collected, concentrated,and dried. Product is characterized by TLC, HPLC, NMR, and/or MS.

[0120] 4.3 Pharmaceutical Compositions and Methods of Use

[0121] The pharmaceutical compositions containing the novel prodrugs asactive ingredients may be any pharmaceutically acceptable dosage formsknown in the art which do not completely diminish the activity of thetaxane prodrugs. Examples include oral, injectable or intravenous dosageforms. Each dosage form comprises an effective amount of a prodrug ofthe invention and pharmaceutically inert ingredients, e.g., conventionalexcipients, vehicles, fillers, binders, disintegrants, solvents,solubilizing agents, sweeteners, coloring agents and any other active orinactive ingredients which are regularly included in pharmaceuticaldosage forms. Suitable oral dosage forms include tablets, capsules,caplets, gelcaps, pills, liquid solutions, suspensions or elixirs,powders, lozenges, micronized particles and osmotic delivery systems.Suitable injectable and IV dosage forms include isotonic salinesolutions or dextrose solutions containing suitable buffers andpreservatives. Many such dosage forms and vehicles, and listings ofinactive ingredients are well known in the art and are set forth instandard texts such as The Pharmaceutical Codex: Principles and Practiceof Pharmaceutics, 12^(th) edition (1994).

[0122] The taxane prodrugs of the present invention can be administeredin such oral (including buccal and sublingual) dosage forms as tablets,capsules (each including timed release and sustained releaseformulations), pills, powders, granules, elixirs, tinctures,suspensions, syrups and emulsions. Likewise, they may also beadministered in nasal, ophthalmic, otic, rectal, topical, intravenous(both bolus and infusion), intraperitoneal, intraarticular, subcutaneousor intramuscular inhalation or insufflation form, all using forms wellknown to those of ordinary skill in the pharmaceutical arts.

[0123] The dosage regimen utilizing the taxane prodrugs of the presentinvention is selected in accordance with a variety of factors includingtype, species, age, weight, sex and medical condition of the patient;the severity of the condition to be treated; the route ofadministration; the renal and hepatic function of the patient; and theparticular compound or salt thereof employed. An ordinarily skilledphysician or veterinarian can readily determine and prescribe theeffective amount of the drug required to prevent, counter or arrest theprogress of the condition.

[0124] Oral administration is generally preferred for administration toa human. In some cases, a relatively lower dose is sufficient and, insome cases, a relatively higher dose or increased number of doses may benecessary. Topical application similarly may be once or more than onceper day depending upon the usual medical considerations. Advantageously,taxane prodrugs of the present invention may be administered in a singledaily dose, or the total daily dosage may be administered in divideddoses of two, three or four times daily.

[0125] In the methods of the present invention, the taxane prodrugs canform the active ingredient and are typically administered in admixturewith suitable pharmaceutical diluents, excipients or carriers(collectively referred to herein as “carrier” materials) suitablyselected with respect to the intended form of administration, that is,oral tablets, capsules, elixirs, syrups and the like, and consistentwith conventional pharmaceutical practices.

[0126] For instance, for oral administration in the form of a tablet orcapsule, the active drug component can be combined with an oral,non-toxic pharmaceutically acceptable inert carrier such as ethanol,glycerol, water and the like. Powders are prepared by comminuting thecompound to a suitable fine size and mixing with a similarly comminutedpharmaceutical carrier such as an edible carbohydrate, as, for example,starch or mannitol. Flavoring, preservative, dispersing and coloringagent can also be present.

[0127] Capsules are made by preparing a powder mixture as describedabove and filling formed is gelatin sheaths. Glidants and lubricantssuch as colloidal silica, talc, magnesium stearate, calcium stearate orsolid polyethylene glycol can be added to the powder mixture before thefilling operation. A disintegrating or solubilizing agent such asagar-agar, calcium carbonate or sodium carbonate can also be added toimprove the availability of the medicament when the capsule is ingested.

[0128] Moreover, when desired or necessary, suitable binders,lubricants, disintegrating agents and coloring agents can also beincorporated into the mixture. Suitable binders include starch, gelatin,natural sugars such as glucose or beta-lactose, corn sweeteners, naturaland synthetic gums such as acacia, tragacanth or sodium alginate,carboxymethylcellulose, polyethylene glycol, waxes and the like.Lubricants used in these dosage forms include sodium oleate, sodiumstearate, magnesium stearate, sodium benzoate, sodium acetate, sodiumchloride and the like. Disintegrators include, without limitation,starch, methyl cellulose, agar, bentonite, xanthan gum and the like.Tablets are formulated, for example, by preparing a powder mixture,granulating or slugging, adding a lubricant and disintegrant andpressing into tablets. A powder mixture is prepared by mixing the taxaneprodrug, suitably comminuted, with a diluent or base as described above,and optionally, with a binder such as carboxymethylcellulose, analiginate, gelatin, or polyvinyl pyrrolidone, a solution retardant suchas paraffin, a resorption accelerator such as a quaternary salt and/oran absorption agent such as bentonite, kaolin or dicalcium phosphate.The powder mixture can be granulated by wetting with a binder such assyrup, starch paste, acadia mucilage or solutions of cellulosic orpolymeric materials and forcing through a screen. As an alternative togranulating, the powder mixture can be run through the tablet machineand the result is imperfectly formed slugs broken into granules. Thegranules can be lubricated to prevent sticking to the tablet formingdies by means of the addition of stearic acid, a stearate salt, talc ormineral oil. The lubricated mixture is then compressed into tablets. Thetaxane prodrugs of the present invention can also be combined with freeflowing inert carrier and compressed into tablets directly without goingthrough the granulating or slugging steps. A clear or opaque protectivecoating consisting of a sealing coat of shellac, a coating of sugar orpolymeric material and a polish coating of wax can be provided.Dyestuffs can be added to these coatings to distinguish different unitdosages.

[0129] Oral fluids such as solution, syrups and elixirs can be preparedin dosage unit form so that a given quantity contains a predeterminedamount of the compound. Syrups can be prepared by dissolving thecompound in a suitably flavored aqueous solution, while elixirs areprepared through the use of a non-toxic alcoholic vehicle. Suspensionscan be formulated by dispersing the compound in a non-toxic vehicle.Solubilizers and emulsifiers such as ethoxylated isostearyl alcohols andpolyoxy ethylene sorbitol ethers, preservatives, flavor additive such aspeppermint oil or saccharin, and the like can also be added.

[0130] Where appropriate, dosage unit formulations for oraladministration can be microencapsulated. The formulation can also beprepared to prolong or sustain the release as for example by coating orembedding particulate material in polymers, wax or the like.

[0131] The taxane prodrugs of the present invention can also beadministered in the form of liposome delivery systems, such as smallunilamellar vesicles, large unilamellar vesicles and multilamellarvesicles. Liposomes can be formed from a variety of phospholipids, suchas cholesterol, stearylamine or phosphatidylcholines.

[0132] Taxane prodrugs of the present invention may also be delivered bythe use of monoclonal antibodies as individual carriers to which thecompound molecules are coupled. The taxane prodrugs of the presentinvention may also be coupled with soluble polymers, such as targetabledrug carriers. Such polymers can include polyvinylpyrrolidone, pyrancopolymer, polyhydroxypropylmethacrylamide-phenol,polyhydroxyethylaspartamidephenol, or polyethyleneoxidepolylysinesubstituted with palmitoyl residues. Furthermore, the taxane prodrugs ofthe present invention may be coupled to a class of biodegradablepolymers useful in achieving controlled release of a drug, for example,polylactic acid, polepsilon caprolactone, polyhydroxy butyric acid,polyorthoesters, polyacetals, polydihydropyrans, polycyanoacrylates,cross-linked or amphipathic block copolymers of hydrogels, polyasparticacid or polyglutamic acid.

[0133] The present invention includes pharmaceutical compositionscontaining about 0.01 to about 99.5%, more particularly, about 0.5 toabout 90% of a taxane prodrug in combination with a pharmaceuticallyacceptable carrier.

[0134] Parenteral administration can be effected by utilizing liquiddosage unit forms such as sterile solutions and suspensions intended forsubcutaneous, intramuscular or intravenous injection. These are preparedby suspending or dissolving a measured amount of the taxane prodrug in anon-toxic liquid vehicle suitable for injection such as aqueousoleaginous medium and sterilizing the suspension or solution.

[0135] Alternatively, a measured amount of the taxane prodrug is placedin a vial and the vial and its contents are sterilized and sealed. Anaccompanying vial or vehicle can be provided for mixing prior toadministration. Non-toxic salts and salt solutions can be added torender the injection isotonic. Stabilizers, preservations andemulsifiers can also be added.

[0136] Rectal administration can be effected utilizing suppositories inwhich the taxane prodrug is admixed with low-melting water-soluble orinsoluble solids such as polyethylene glycol, cocoa butter, higher esteras for example flavored aqueous solution, while elixirs are preparedthrough myristyl palmitate or mixtures thereof.

[0137] Topical formulations of the present invention may be presentedas, for instance, ointments, creams or lotions, eye ointments and eye orear drops, impregnated dressings and aerosols, and may containappropriate conventional additives such as preservatives, solvents toassist drug penetration and emollients in ointments and creams. Theformulations may also contain compatible conventional carriers, such ascream or ointment bases and ethanol or oleyl alcohol for lotions. Suchcarriers may be present as from about 1% up to about 98% of theformulation. More usually they will form up to about 80% of theformulation.

[0138] For administration by inhalation the taxane prodrugs according tothe invention are conveniently delivered in the form of an aerosol spraypresentation from pressurized packs or a nebulizer, with the use of asuitable propellant, e.g. dichlorodifluoromethane,trichlorofluoromethane, dichlorotetrafluoroethane, tetrafluoroethane,heptafluoropropane, carbon dioxide or other suitable gas. In the case ofa pressurized aerosol the dosage unit may be determined by providing avalve to deliver a metered amount. Capsules and cartridges of e.g.gelatin for use in an inhaler or insufflator may be formulatedcontaining a powder mix of a compound of the invention and a suitablepowder base such as lactose or starch.

[0139] The preferred pharmaceutical compositions are those in a formsuitable for oral administration, such as tablets and liquids and thelike and topical formulations.

[0140] The present invention also provides a method of treating amammalian subject having a tumor, cancer, or other disease conditionresponsive to a taxane (e.g., paclitaxel or docetaxel). This treatmentmethod comprises administering to said subject a pharmaceuticalcomposition containing a pharmaceutically effective amount of ataxane-oligomer prodrug according to the present invention.Taxane-responsive diseases which may be treated by the invention includecancers, tumors, malignancies, uncontrolled tissue or cellularproliferation secondary to tissue injury, polycystic kidney disease andmalaria. Among the cancers which may be treated are hepatocellularcarcinoma, liver metastases, gastrointestinal cancers, lymphoma,leukemia, melanoma, Kaposi's sarcoma, and cancers of the pancreas,kidney, cervix, breast, ovary, brain, prostate, and urogenitalcarcinoma.

[0141] The taxane prodrugs of the invention may be administered byintravenous administration, infusion, non-intravenous injection,intraperitoneally and by injection of a bolus. The taxane prodrugs mayalso be administered orally to the patient in a suitable dosage formalone or together with an oral bioavailability-enhancing agent. Suchbioavailability-enhancing agent may be selected from the groupconsisting of cyclosporins A through Z, (Me-lle-4)-cyclosporin, dihydrocyclosporin A, dihydro cyclosporin C, acetyl cyclosporin A, genisteinand related isoflavonoids, quercetin, calphostin, ceramides, morphineand morphine congeners. Preferred enhancing agents are cyclosporin A,cyclosporin C, cyclosporin D, cyclosporin F, dihydro cyclosporin A,dihydro cyclosporin C, acetyl cyclosporin A, and B cyclodextrin.

[0142] Further, the taxane prodrugs of the present invention may beadministered alone or with other is chemotherapeutic agents (e.g.,anti-cancer agents). Where the paclitaxel-PEG prodrugs of the presentinvention are administered with other chemotherapeutic agents, thepaclitaxel-PEG prodrugs and other chemotherapeutic agents may beadministered simultaneously or sequentially. Additionally, thepaclitaxel-PEG prodrugs of the present invention may be administeredbefore, after or simultaneously with radiation therapy.

[0143] In one aspect, the present invention provides a treatment forcancer comprising administering to a subject a combination of the taxaneprodrugs of the present invention and cisplatin. Preferably the canceris ovarian cancer, and preferably the taxane prodrug comprisespaclitaxes and is administered before cisplatin. Paclitaxel has beenshown to be effectively administered with cisplatin. Neutropenia hasbeen shown to be a dose limiting effect of coadministration ofpaclitaxel and cisplatin. Clinical trials have demonstrated that lessneutropenia occurs when paclitaxel is administered before cisplatin. Forexample, while preferred doses of paclitaxel-PEG prodrug are up to 350mg/m² followed, by cisplatin (75 mg/m²), more preferred doses arepaclitaxel-PEG prodrug (25 mg/ml), followed by cisplatin (75 mg/ml) andG-CSF at standard doses (5 μg/kg/d subcutaneously).

5. EXAMPLES

[0144] 5.1 2′-Succinylpaclitaxel

[0145] The following protocol is an improved version of the procedure ofDeutsch, et. al. To a mixture of 5.00 g (5.86 mmol) of paclitaxel and5.86 g (58.6 mmol) of succinic anhydride was added 110 mL of anhydrouspyridine. After stirring the resulting solution at room temperature for5 h, thin layer chromatography (TLC) analysis indicated completeconsumption of the paclitaxel. The solvent was removed under reducedpressure by means of rotary evaporation and the residue was dried invacuo for 2 h. The resulting waxy semisolid was stirred efficiently with200 mL of water, affording a flocculent white solid, which was collectedby suction filtration on a Buchner funnel. The solid was washed withwater then allowed to suck dry for 30 mm., then dried at roomtemperature in vacuo in a dessicator over P₂O₅ for 15 h. The white solidwas taken up in 30 mL of acetone, then with efficient stirring, 30 ml ofwater was slowly added. The resulting thick white paste was well-blendedfor 15 mm, suction filtered through a Buchner funnel rinsing with excesswater, and allowed to suck dry for 1 h. The resulting moist white solidwas carefully dried at room temperature in vacuo in a dessicator overP₂O₅ for 18 h. As the solid became more dry and less coagulated duringthis drying period, the P₂O₅ was replenished and the solid wasperiodically broken into smaller pieces until a moderately fine powderwas obtained (5.29 g, 95% yield). Analytical HPLC analysis indicatedthis material to be of 97% purity. MS (FAB+) m/z (rel. inten.) 954 (M⁺,100), 570 (15), 509 (64).

[0146] 5.2 2′-Succinamidyl-PEG2-amine-paclitaxel Trifluoroacetate

[0147] A mixture of 200 mg (0.2 10 mmol) of 2′-succinylpaclitaxel(Compound 2) and 47 mg (0.273 mmol, 95% purity) of1,1′-carbonyldiimidazole under nitrogen was dissolved in 2.9 mL ofanhydrous acetonitrile. A gas outlet needle was inserted through thereaction flask septum such that a moderate flow of nitrogen wasmaintained to flush out carbon dioxide gas. The reaction vessel waslowered into an oil bath preheated to 48° C., causing gas evolution.After stirring efficiently for 15 min, the reaction vessel was removedfrom the oil bath and allowed to cool to room temperature. The amount ofacetonitrile lost to evaporation was replenished. The nitrogen outletneedle was removed such that a static atmosphere of nitrogen wasmaintained. A solution of 37 μL (0.252 mmol) of2,2′-(ethylenedioxy)bis(ethylamine) in 1.4 mL of acetonitrile was addeddropwise. After 45 min., a solution of 81 μL (1.05 mmol) oftrifluoroacetic acid in 0.7 mL of acetonitrile was added dropwise. Theresulting crude reaction solution typically contains a 70-74% yield ofthe desired trifluoroacetate product (Compound 3), as determined byanalytical HPLC analysis.

[0148] 5.3 Preparative HPLC Purification of Trifluoroacetate (Compound3)

[0149] The product was generally purified by prep HPLC by combining theproduct-containing fractions.

[0150] 5.3.1 Improving HPLC Resolution

[0151] Medium Scale Reaction. To improve HPLC resolution on a mediumscale, the crude reaction solution was diluted by adding water withoutcausing precipitation. Thus, to an aliquot of 3.30 mL of the abovereaction solution was slowly added 4.03 mL of water with efficientstirring, consequently affording a solution consisting of 55% water. Theresulting slightly hazy mixture was filtered through a 0.45 μm Gelmanacrodisc 13 syringe filter, then chromatographed on a Waters 600E HPLCsystem using a reverse phase Vydac column (22 mm×250 mm, C 18, 300 Å,10-15μ). The mobile phase was an acetonitrile-water solution containing0.1% (v/v) trifluoroacetic acid. Major fractions containing desiredproduct of >97% purity were obtained using a gradient elution, from40:60 to 45:55, acetonitrile:water with 0.1% (v/v) TFA over 30 minutesat a flow rate of 5 mL/mm. Subsequent isocratic elution with 90:10,acetonitrile:water containing 0.1% (v/v) TFA removed unidentified sideproducts in preparation for subsequent chromatographic runs.

[0152] For analytical purposes, the purified fractions resulting fromthe above-described amidation reaction protocol [200 mg (0.210 mmol)scale of 2′-succinylpaclitaxel (2)] were concentrated under reducedpressure by means of rotary evaporation with gradual bath warming to 55°C., then dried in vacuo at room temperature to obtain 170 mg (68% yield)of trifluoroacetate (Compound 3) as an amorphous white solid. ¹H NMR(300 MHz, CDCl₃) δ8.10 (2H, d, J=7.2 Hz), 7.99-7.81 (2H, m), 7.66-7.20(11H, m), 6.92 (1H, brs), 6.28 (1H, s), 6.07 (1H, t, J=10.0 Hz), 5.86(1H, dd, J=3.9, 5.0 Hz), 5.65 (1H, d, J=6.9 Hz), 5.42 (1H, d, J=5.4 Hz),4.94 (1H, d, J=8.2 Hz), 4.36 (1H, m), 4.29 (1H, d, J=8.5 Hz), 4.16 (1H,d, J=8.5 Hz), 3.74 (1H, d, J=6.9 Hz), 3.66-3.04 (16H, m), 2.80-2.60 (2H,in), 2.38 (3H, s), 2.220 (3H, s), 1.84 (3H, s), 1.66 (3H, s), 1.20 (3H,s), 1.13 (3H, s); MS (FAB+) m/z 1084 (M⁺)

[0153] Larger Scale Reaction. A larger scale amidation reaction solutionconsisting of 1,000 mg (1.05 mmol) of 2′-succinylpaclitaxel (Compound2), 27 mL total volume was shown to contain 44% of desiredtrifluoroacetate product (Compound 3) by analytical HPLC analysis. A10.0 mL aliquot was concentrated under reduced pressure by means ofrotary evaporation just to the point of affording a slightly viscousyellow oil. The oil was dissolved by adding 1.0 mL of acetonitrile,filtered through a 0.45 μm Gelman acrodisc 13 syringe filter, thenchromatographed on a Waters 600E HPLC system using a reverse phase Vydaccolumn (50 mm×250 mm, C18, 300 Å, 10-15μ). The mobile phase was anacetonitrile-water solution containing 0.1% (v/v) trifluoroacetic acid.Major fractions containing desired product of >97% purity were obtainedusing a gradient elution, from 40:60 to 45:55, acetonitrile:water with0.1% (v/v) TFA over 30 minutes at a flow rate of 26 mL/min. Subsequentisocratic elution with 90:10, acetonitrile:water containing 0.1% (v/v)TFA removed unidentified side products in preparation for subsequentchromatographic runs.

[0154] The fractions determined by analytical HPLC analysis to be ofhigh purity were combined with analogous preparative HPLC runs toprovide a combined solution of 870 mL total volume containingtrifluoroacetate (Compound 3) of >97% purity. The solution was useddirectly (without concentration) in the ion exchange chromatographystep.

[0155] 5.4 Stability of Trifluoroacetate (Compound 3)

[0156] It was observed that several trifluoroacetate product fractionsolutions obtained from a preparative HPLC run initially of an averagepurity of 98.8% changed to an average of 97.4% purity after storage at8° C. for 16 days, as determined by analytical HPLC analysis.

[0157] 5.4.1 Determination of Aqueous Solubility of Trifluoroacetate(Compound 3)

[0158] To a sample of 2.5 mg of trifluoroacetate (Compound 3) in a smallvial was added 200 μL of deionized water. The vial was capped and theresulting mixture was ultrasonicated for 15 minutes. The resultingcloudy mixture was filtered through a 0.45μ Gelman acrodisc 13 syringefilter. The filtrate was weighed (140 mg) and was lyophilized to provide1.4 mg of a white fluffy solid. Thus, assuming that the aqueous solutionis of density 1.00, the water solubility of trifluoroacetate (Compound3) is 7.4 mg/mL (i.e. 1.4 mg/0.190 mL).

[0159] 5.5 Ion Exchange Chromatography of Trifluoroacetate Anion forAcetate Anion: Acetate Prodrug (Compound 4)

[0160] For preparative purposes, fraction solutions of trifluoroacetate(Compound 3) of >97% purity obtained from a preparative HPLCpurification protocol described above were combined and taken ondirectly to ion chromatography without concentration. For example,combined preparative HPLC fractions of 870 mL total volume theoreticallycontaining 0.462 mmol of substrate and containing 11.3 mmol of TFA (0.1%(v/v)) was used for the following ion exchange protocol:

[0161] A 92 g portion of DOWEX® 1×8-400 (strongly basic, chloride form)ion exchange resin was washed three times with 270 mL each of deionizedwater, each time decanting away the yellow suspended matter and the bulkof the rinse water. To obtain the resin in its acetate form, theresulting slurry was stirred with a solution of 1,882 g of NaOAc.3H₂O in4.00 L of deionized water for 1.0 h. The resin was collected by suctionfiltration on a Buchner funnel and washed several times with a total of1.84 L of deionized water. The resin was washed two times with 750 mLeach of 0.013 M HOAc (aq) [i.e. 0.1% (v/v) HOAc, by analogy to 0.1%(v/v) TFA used in the preparative HPLC protocols], suction filtered on aBuchner funnel, then allowed to suck dry for 10 min. The resin wassuspended in 0.013 M HOAc (aq), poured into a glass flash chromatographycolumn, then eluted using gentle air pressure with 200 mL of 0.013 MHOAc (aq), thus giving a 10 cm high×3.8 cm diameter resin column, whichwas then topped off with ca. 4 cm of sand. The column was then elutedwith 250 mL of acetonitrile, then with 250 mL of 0.013 M HOAc (aq). The870 mL volume of the trifluoroacetate (3) solution was made to be 0.013M in HOAc by the addition of a solution of 0.63 mL of glacial aceticacid in 10 mL of acetonitrile with efficient stirring. The solution wasapplied to and eluted through the column using gentle air pressure.Fraction collection was commenced immediately using 50 mL test tubes.Once the entire 870 mL of solution had completely passed into/throughthe resin, the column was further eluted with 0.013 M HOAc (aq). Thefractions containing product of >97% purity (as determined by analyticalHPLC analysis at 210 nm) were combined and concentrated under reducedpressure by means of rotary evaporation with gradual bath warning to 55°C. and dried in vacuo at room temperature for 16 h to provide anoff-white amorphous residue. The residue was scraped with a spatula fromthe flask into a fine amorphous powder. The remnants not scraped out ofthe flask could be further procured without alteration of product purityby transferring to a smaller flask with the aid of a minimal amount of0.013 M HOAc (aq) as solvent, concentrating as described above, thenscraping with a spatula to provide additional product, which wascombined and dried at room temperature in vacuo in a dessicator overP₂O₅ for 24 h to provide acetate prodrug (Compound 4) (293 mg, 24%unoptimized yield overall of material of >97% purity) as a yellowpowder. Combination of the fractions of <97% purity in a manner similarto the method described above afforded 146 mg (12% unoptimized yield) ofadditional acetate (Compound 4). Analyses of the products by analyticalion chromatography [Quantitative Technologies, Inc., (QTI)] did not showthe presence of any trifluoroacetic acid (TFA analysis: below detectionlimit of 100 ppm). mp 114-117° C.; ¹H NMR (300 MHz, CDCl₃) δ8.11(2H, d,J=7.2 Hz), 7.85 (2H, d, J=7.7 Hz), 7.62-7.36 (11H, m), 6.29 (1H, s),6.11 (1H, t, J=10.0 Hz), 5.87 (1H, dd, J=3.9, 4.4 Hz), 5.65 (1H, d,J=6.9 Hz), 5.44 (1H, d, J=4.9 Hz), 4.95 (1H, d, J=9.5 Hz), 4.38 (1H, m),4.28 (1H, d, J=8.5 Hz), 4.18 (1H, d, J=8.2 Hz), 3.76 (1H, d, J=6.4 Hz),3.63-3.34 (16H, m), 3.04 (2H, brs), 2.75 (2H, in), 2.53 (2H, m), 2.40(3H, s), 2.20 (3H, s), 2.01 (3H, s), 1.87 (3H, s), 1.67 (3H, s), 1.20(3H, s), 1.13 (3H, s); MS (FAB+) m/z (rel. inten.) 1084 (M⁺).

[0162] 5.6 General Solubility of Acetate (Compound 4)

[0163] Acetate (Compound 4) is highly soluble in CDCl₃ and sparinglysoluble in diethyl ether and in hexanes. Three separate samples of 3.0mg each of acetate (Compound 4) afforded a homogeneous solution in 81 μLof 100% anhydrous ethanol, in 81 μL of acetone, and in 81 μL of 0.5 Maqueous acetic acid. Thus, the solubility in each of these threesolvents must be some value equal to or greater than 37 mg/mL (i.e. 3.0mg/0.081 mL).

[0164] 5.7 Determination of Aqueous Solubility of Acetate (Compound 4)by Mass

[0165] To a sample of 10.0 mg of acetate (Compound 4) in a small vialwas added 176 μL of deionized water. The vial was capped and theresulting mixture was ultrasonicated for 15 minutes. The resultingliquid was shown to contain acetate (Compound 4) in 98.7% purity byanalytical HPLC analysis at 210 nm. The liquid was filtered through a0.45μ cellulose acetate syringe filter. The mass (76 mg) of a knownvolume (75 μL) of the filtrate was measured to determine that thedensity of the solution was 1.01 g/mL. The filtrate was shown to containacetate (Compound 4) in 98.8% purity by analytical HPLC analysis at 210nm. A 118 mg quantity of the filtrate was lyophilized to provide 6.4 mgof an off-white fluffy solid. Thus, by this method the water solubilityof acetate (Compound 4) was determined to be 55 mg/mL (i.e. 6.4 mg/0.117mL).

[0166] 5.8 Determination of Aqueous Solubility of Acetate (Compound 4)by Analytical HPLC

[0167] To a sample of 10.0 mg of acetate (Compound 4) in a small vialwas added 150 μL of deionized water. The vial was capped, vortexed for 3mm., and ultrasonicated for 15 minutes. The resulting viscous paleyellow/orange mixture was slowly and carefully taken up into a 1 mLsyringe and then firmly filtered through a 0.45μ cellulose acetatesyringe filter, thus affording a viscous homogeneous yellow/orangesolution. A 75 μL portion of the filtrate was diluted 88-fold withacetonitrile and then analyzed by analytical HPLC at 229 nm and 270 nm.The area under the curve observed at 229 nm and 270 nm was respectivelycompared to both a 3-point calibration curve obtained at 229 nm(r²=0.99999) and a 5-point curve obtained at 270 nm (r²=0.99996). Thus,by this method, the water solubility of acetate (Compound 4) wasdetermined to be 40.1 mg/mL (at 229 nm) and 39.7 mg/mL (at 270 nm).

[0168] 5.9 Chemical Hydrolysis Behavior of Acetate (Compound 4)

[0169] A sample of solid acetate (Compound 4) was dissolved (ca. 1mg/mL) in wet acetonitrile (nonanhydrous due to exposure to humid air).Over the course of 26 days at room temperature, acetate (Compound 4)smoothly converted quantitatively into paclitaxel (1) with nosignificant side product formation, as observed by analytical HPLCanalysis (see FIG. 1).

[0170] 5.9.1 Chemical Hydrolysis Behavior of Acetate (Compound 4) atVarious pH

[0171] To many 13 mm×100 mm glass test tubes was added 5.15 μL each ofan 8.741×10⁻⁴ M aqueous solution of acetate prodrug (Compound 4). Toeach tube was then added 295 μL of aqueous solutions of phosphatebuffered saline (PBS) of pH 8.00, 7.40, 7.00 and 5.80 and an aceticacid/formic acid buffered solution of pH 2.00. The tubes were capped andincubated at 37° C. in a reciprocal water bath shaker. After incubationfor various appropriate time intervals, a test tube was removed from theshaker, 900 μL of acetonitrile was added, and the sample was vigorouslyvortexed for 3 minutes. The resulting solutions were analyzed byanalytical HPLC to generate hydrolysis rate data (see table and graphs,below).

[0172] 5.10 In Vitro Prodrug Hydrolysis of Acetate (Compound 4)

[0173] To nine 13 mm×100 mm test tubes was added 5.15 μL each of an8.741×10⁻⁴ M aqueous solution of acetate prodrug (Compound 4). To eachtube was then added 295 μL of freshly obtained heparinized rat plasmafrom an adult male Sprague Dawley rat (CD) (source Charles River;Raleigh, N.C.). The tubes were capped and incubated at 37° C. in areciprocal water bath shaker. After incubation for various timeintervals, a test tube was removed from the shaker, 900 μL ofacetonitrile was added, the sample was vigorously vortexed for 3 minutesand then cooled to −12° C. for between 30 and 90 minutes. The sampleswere centrifuged at 25° C. for 10 minutes at 1,600 g and the resultingclear colorless supernatant solution was analyzed by analytical HPLC(see FIG. 2).

[0174] 5.11 2′-Succinamidyl-PEG2-amine-paclitaxel Acetate

[0175] A mixture of 200 mg (0.210 mmol) of 2′-succinylpaclitaxel(Compound 2) and 47 mg (0.273 mmol) of 1,1′-carbonyldiimidazole undernitrogen was dissolved in 5 mL of anhydrous acetonitrile. The reactionvessel was lowered into an oil bath preheated to 48° C., causing gasevolution. After stirring for 15 min, the reaction vessel was allowed tocool to room temperature. A solution of 37 μL (0.252 mmol) of2,2′-(ethylenedioxy)bis-(ethylamine) in 2 mL of acetonitrile was addeddropwise, then after 1 h a solution of acetic acid (1.05 mmol) in 1 mLof acetonitrile was added. The resulting crude reaction solutionobtained by this method typically contains a 75% yield of desiredacetate product, as determined by analytical HPLC analysis.

[0176] 5.12 Preparative HPLC Purification of2′-Succinamidyl-PEG2-amine-paclitaxel Acetate

[0177] The crude compound from Example 5.11 was chromatographed on aWaters Prep LC 4000 system, using a reverse phase Vydac column (22mm×250 mm, C18, 300□, 10-15μ). The product was purified by combining theproduct-containing fractions obtaining from preparative HPLC. Majorfractions containing desired product (>97% purity) were obtained using agradient elution, from 30:70 to 95:5, acetonitrile:water with 0.1%(v/v)acetic acid over 35 min. The purified fraction were concentrated underreduced pressure by means of rotary evaporation, then lyophilized toobtain white solid. MS (FAB+) m/z 1084 (M⁺).

[0178] 5.13 2′-Glutaramidyl-PEG2-amine-paclitaxel Acetate

[0179] 2′-Glutarylpaclitaxel is synthesized using the proceduredescribed above in Example 5.1 by substituting glutaric anhydride forsuccinic anhydride. 2′-Glutaramidyl-PEG2-amine-paclitaxel acetate(Compound 5) is then synthesized using the procedure described above inExample 5.11 by using 2′-glutarylpaclitaxel instead of2′-succinylpaclitaxel as a starting material. The chemical structure ofcompound 5 is shown below.

[0180] 5.14 Preparative HPLC Purification of2′-Glutaramidyl-PEG2-amine-paclitaxel Acetate

[0181] Preparative HPLC purification of2′-glutaramidyl-PEG2-amine-paclitaxel acetate is performed using theprocedure described above in Example 5.12.

[0182] 5.15 Effect of Compounds of the Present Invention on theNIH:OVCAR-3 Cell Line

[0183] The purpose of this experiment was to investigate the effect of afull dose response of Paclitaxel (tested for comparison purposes only,not a compound of the present invention), TX-001 (Compound 4, describedabove in Example 5.5), and TX-002 (Compound 5, described above inExample 5.13) on the NIH:OVCAR-3 cell line. NIH:OVCAR-3 cells, which area human ovarian cancer cell line, were removed from a T75 flask byversene and counted via a hemacytometer. The cells were then pelleted bycentrifugation (1000 RPM for 10 minutes). The supernatant was removedand fresh media (RPMI 1640 w/10% FCS and 1% L-glutamine) was added tobring cell concentration to 10,000 cells/mL. Then 0.1 mL (1000 cells) ofthe 10,000 cell/mL solution was added to individual wells of a 96 welledflat bottom plate. This plate was then placed overnight in a 37° C. with5% CO₂ incubator to allow cells time to adhere to bottom of wells. Thenext day Paclitaxel, TX-001, and TX-002 were diluted in fresh media tothe following concentrations: 1000, 500, 200, 50, 10, 5, 1 and 0.5 nM.Next 0.1 mL of the appropriate drug concentration was added toappropriate column of 96 welled plate (n=8) making final concentrationsof 500, 250, 50, 25, 5, 2.5, 0.5, and 0.25 nM. One column on each platereceived 0.1 mL of fresh media and served as the untreated control.These plates were then placed in the 37° C. with 5% CO₂ incubator for 6days. After 6 day incubation, all wells were aspirated and plates wereplaced in a −70° C. freezer for 2 hours. Also an appropriate number ofcells were removed from another T75 flask in the same fashion asmentioned above but this time after centrifugation the supernatant wasremoved and the tube was placed in a −70° C. freezer for 2 hours. Theplates and tube were thawed at room temperature and then the CyQuantassay (Molecular Probes) was performed. The tube was resuspended with anappropriate amount of the CyQuant GR dye/cell lysis buffer and dilutedaccordingly to create a standard curve. Next 0.2 mL of each standardconcentration was placed in duplicate in a new 96 well plate. This platewas then placed in the dark for 3 minutes. Finally all wells of the 96well plates that were previously frozen and thawed received 0.2 mL ofCyQuant GR dye/cell lysis buffer and as well were placed in dark for 3minutes. The fluorescence was then measured at 485 nm excitation and 538nm emission. Cell number per each well was then calculated from thestandard curve. Means were calculated for each concentration of drug andthen were divided by the mean of the untreated wells for each particularplate. The results are shown in FIG. 3 and expressed in % growth tountreated cells.

[0184] 5.16 Effect of Compounds of the Present Invention on theProduction of Activated Caspase-3 by the NIH:OVCAR-3 Cell Line

[0185] The purpose of this experiment was to investigate the effect of50 nM Paclitaxel, TX-001, and TX-002 on the production of activatedCaspase-3 by the NIH:OVCAR-3 cell line. 7 T75 flasks with approximately70-80% NIH:OVCAR-3 cell confluence were used for this experiment. Eachflask was rinsed with 5 mL of PBS then 15.0 mL of appropriate drug wereadded to each flask. These flasks were then placed in a 37° C. with 5%CO₂ incubator until desired time point was achieved. Each T75 flask wasthen 0.05% Trypsin treated and cells were counted via a hemacytometer.The cells were then pelleted by centrifugation (1000 RPM for 10minutes). The amount of active Caspase-3 was then determined by theCaspase-3 Fluorometric Assay (R&D Systems). The supernatant was removedfrom the pelleted cells and 25 μL of cold Cell Lysis Buffer is added forevery 1,000,000 cells/mL. This cell lysate was incubated on ice for 10minutes and then 50 μL from each condition is added in duplicate to a 96well flat bottom plate. Next 50 μL of 2× Reaction Buffer and 5 μL ofCaspase-3 fluorogenic substrate (DEVD-AFC) were added to each well. Theplate was then placed in a 37° C. with 5% CO₂ incubator for 1.5 hours.Finally the fluorescence was then measured at 400 nm excitation and 505nm emission. Data was then plotted as active Caspase-3 Fluorescence asillustrated in FIG. 4.

[0186] 5.17 Evaluation of the Anti-Tumor Activity of Compounds 4 and 5Against a Series of Human Tumor Cell Lines In Vitro

[0187] HT-1080 and HT-1080/DR4 (MRP/LRP positive) fibrosarcoma celllines (1,2) were obtained from Dr. Y. Rustum, Roswell Park CancerInstitute, Buffalo, N.Y. The A121 ovarian cell line (3) was provided byDr. Kent Crickard, Buffalo General Hospital, Buffalo, N.Y. TheMDA435/LCC6-WT and MDR1 transfected cell lines (4) were provided by Dr.R. Clarke, Lombardi Cancer Center, Georgetown University School ofMedicine. Cell lines were propagated as monolayers in RPMI-1640containing 5% FCS, 5% NuSerum IV, 20 mM HEPES, 2 mM L-glutamine at 37°C. in a 5% CO₂ humidified atmosphere.

[0188] Paclitaxel, which was used for comparison purposes and is not acompound of the present invention, was provided by Dr. I. Ojima, SUNY atStonybrook. TX-001 (Compound 4) and TX-002 (Compound 5) (CD#20027 and20028 respectively) were provided by NOBEX.

[0189] Paclitaxel was solubilized in 100 % DMSO. TX-001 and 002 weresolubilized in sterile H₂O acidified with 10% 1 N HCl. For the firstexperiment, 4.0 mM stocks of TX-001 and 002 were prepared. Solutions ofTX-001 and TX-002 contained clear needle-like and cast-like precipitatesand were fairly viscous (Experiment 1). For the second experiment(Experiment 2), less concentrated stock solutions (0.4 mM) of eachcompound were prepared in sterile H₂O acidified with 10% 1 N HCl. Thesame type of precipitates were noted, however neither solution wasviscous. All compounds were further diluted in RPMI-1640 containing 10mM HEPES.

[0190] Assessment of cell growth inhibition was determined in 96 wellmicrotiter plates according to the method of Skehan et al., “NewColorimetric Cytotoxicity Assay for Anticancer-Drug Screening, Articles82(13):1107-1112 (1990). Briefly, cells were plated with 400-1800cells/well in 96 well plates and incubated at 37° C. 15-18 hr prior todrug addition to allow for cell attachment. Each cell line was exposedto 12 concentrations of compound (a 6 log range), 5 replicate datapoints per compound concentration. Cells were exposed to compoundconcentrations ranging from 0.003 to 1000 nM for paclitaxel and 0.03 to10000 nM for TX-001 and TX-002. Cells were cultured for a total of 3-4cell doublings (72-96 h). Assays were terminated with 100 μL of ice-cold50% TCA. After 1 hr at 4° C., plates were washed 5 times with tap waterto remove TCA, low-molecular-weight metabolites and serum proteins. 50μl of 0.4% sulforhodamine B (SRB) was added to each well. Following afive minute incubation at room temperature, plates were rinsed 5 timeswith 0.1% acetic acid and air dried. Bound dye was solubilized with 10mM Tris Base (pH 10.5) for 5 min on a gyratory shaker. Optical densitywas measured at 570 nm.

[0191] Data were fit with the Sigmoid-Emax concentration-effect model(N. H. G. Holford and L. B. Scheiner, “Understanding the dose-effectrelationship: Clinical applications of pharmacokinetic-pharmacodynamicmodels,” Clin. Pharmacokin. 6:429-453 (1981)) with nonlinear regression,weighted by the reciprocal of the square of the predicted response. Thefitting software was developed at RPCI with Microsoft FORTRAN, and usesMarquardt algorithm (D. W. Marquardt, “An algorithm for least squaresestimation of nonlinear parameters,” J. Soc. Ind. Appl. Math.11:431-441) as adapted by Nash (J. C. Nash, Compact Numerical Method forComputers: Linear Algebra and Function Minimization, New York: JohnWiley & Sons, 1979) for the nonlinear regression. The concentration ofdrug that resulted in 50% growth inhibition (IC₅₀) was calculated and isshown in Table I below. TABLE I Effect of Paclitaxel, TX-001 and TX-002on Human Tumor Cell Growth IC50 nM (±S.E.)¹ Compound Experiment A121LCC6-WT LCC6-MDR HT-1080 HT-1080-DR4 Paclitaxel 1 11 ± 0.5 4.7 ± 0.5 434 ± 28 4.5 ± 0.2 4.9 ± 0.4 2 14 ± 1.3 6.0 ± 2.0  391 ± 52 5.7 ± 0.37.7 ± 0.1 TX-001 1 13 ± 0.5 4.9 ± 0.5  337 ± 20 4.5 ± 0.4 8.9 ± 0.4 2.7± 0.4²  269 ± 31 2 37 ± 1.2  13 ± 0.5  404 ± 63  19 ± 0.7 36 ± 1.5TX-002 1 48 ± 3.0  18 ± 1.1 1073 ± 45  22 ± 0.9 32 ± 1.5  16 ± 2.0²  879± 78² 2 171 ± 8.8   38 ± 4.6 1798 ± 168  49 ± 6.5 54 ± 5.3

[0192] TX-001, TX-002 and paclitaxel were evaluated for tumor cellgrowth inhibition using a panel of human tumor cell lines including A121ovarian, breast tumor cell lines LCC6 and the LCC6-MDR1 variant, whichwas transfected with the MDR1 gene and over-expresses P-glycoprotein.These compounds were also evaluated against an MRP/LRP expressing,multidrug resistance HT1080/DR4 human sarcoma cell line.

[0193] TX-001 and TX-002 are active agents against a number of humantumor cell types, with IC50 values ranging between 2.7-1798 nM (TableI). TX-001 appears to be more potent than TX-002 with a growthinhibition profile nearly identical to that of paclitaxel.

[0194] Resistance ratios (IC50 resistant cell line/IC50 parental line)in the LCC6-MDR1 variant line which overexpresses Pgp were similar forthe three compounds tested. They ranged from 65-92 fold for paclitaxel,30-100 fold for TX-001 and 47-60 fold for TX-002. Resistance ratios inthe MRP/LRP expressing mutidrug resistant HT1080/DR4 cell line were alsosimilar ranging from 1.1-1.4 fold for paclitaxel, 1.9-2.0 fold forTX-001 and 1.1-1.5 fold for TX-002.

[0195] Re-testing of TX-001 and TX-002 from stock solutions which hadbeen stored at 40° C. for 7 days, demonstrated a small increase ofactivity in LCC6 and LCC6-MDR1 cells. Testing with non-viscous stocksolutions (0.4 mM) of TX-001 and TX-002 showed slightly less potency inall of the cell lines tested as compared to the initial results andrepeat testing results of the 4.0 mM stock solutions.

[0196] Both TX-00 1 and TX-002 are active agents with TX-00 1 being themore potent.

[0197] The foregoing embodiments and examples are illustrative of thepresent invention and are not to be construed as limiting thereof. Theinvention is defined by the following claims, with equivalents of theclaims to be included therein.

That which is claimed is:
 1. A taxane prodrug comprising a taxane joinedby a hydrolyzable bond to an oligomer having the following structure:

wherein n is from 1 to 12, m is from 2 to 25, p is from 2 to 12, X⁺ is apositive ion and Z⁻ is a negative ion.
 2. The taxane prodrug accordingto claim 1, wherein the taxane is paclitaxel.
 3. The taxane prodrugaccording to claim 2, wherein the oligomer is joined to the 2′ positionof the paclitaxel.
 4. The taxane prodrug according to claim 1, whereinthe taxane is docetaxel.
 5. The taxane prodrug according to claim 1,wherein the taxane is a paclitaxel analog that retains some or all ofthe therapeutic activity of paclitaxel.
 6. The taxane prodrug accordingto claim 1, wherein the taxane is derivatized by 2, 3 or 4 of theoligomers of Formula
 12. 7. The taxane prodrug according to claim 1,wherein the positive ion is selected from the group consisting of NH₃ ⁺and trisubstituted sulfur and the negative ion is selected from thegroup consisting of chloro anion, bromo anion, iodo anion, phosphateanion, acetate anion, trifluoracetate anion, carbonate anion, sulfateanion, and mesylate anion.
 8. The taxane prodrug according to claim 1,wherein n is from 2 to
 4. 9. The taxane prodrug according to claim 8,wherein m is from 2 to 10 and p is from 2 to
 4. 10. The taxane prodrugaccording to claim 1, wherein the taxane prodrug has an aqueoussolubility that is greater than 30 mg/ml.
 11. A pharmaceuticalcomposition comprising: a taxane prodrug according to claim 1; and apharmaceutically acceptable carrier.
 12. A method of treating amammalian subject having a taxane-responsive disease conditioncomprising administering to the subject an effective disease treatingamount of the taxane prodrug according to claim
 1. 13. The methodaccording to claim 12, wherein the administering of the taxane prodrugcomprises orally administering the taxane prodrug.
 14. The methodaccording to claim 12, wherein the disease condition is cancer.
 15. Themethod according to claim 12, wherein the disease condition is ovariancancer or breast cancer.
 16. The method according to claim 15, furthercomprising co-administering cisplatin or doxorubicin with the taxaneprodrug.
 17. The method according to claim 16, wherein theco-administering of cisplatin or doxorubicin with the taxane prodrugcomprises simultaneously co-administering cisplatin with the taxaneprodrug.
 18. The method according to claim 16, wherein theco-administering of cisplatin or doxorubicin with the taxane prodrugcomprises sequentially co-administering cisplatin with the taxaneprodrug.
 19. A taxane prodrug comprising a taxane joined by ahydrolyzable bond to an oligomer having the following structure:


20. The taxane prodrug according to claim 19, wherein the taxane ispaclitaxel.
 21. The taxane prodrug according to claim 20, wherein theoligomer is joined to the 2′ position of the paclitaxel.
 22. The taxaneprodrug according to claim 19, wherein the taxane is docetaxel.
 23. Thetaxane prodrug according to claim 19, wherein the taxane is a paclitaxelanalog that retains some or all of the therapeutic activity ofpaclitaxel.
 24. The taxane prodrug according to claim 19, wherein thetaxane is derivatized by 2, 3 or 4 of the oligomers.
 25. Apharmaceutical composition comprising: a taxane prodrug according toclaim 19; and a pharmaceutically acceptable carrier.
 26. A method oftreating a mammalian subject having a taxane-responsive diseasecondition comprising administering to the subject an effective diseasetreating amount of the taxane prodrug according to claim
 19. 27. Themethod according to claim 26, wherein the administering of the taxaneprodrug comprises orally administering the taxane prodrug.
 28. Themethod according to claim 26, wherein the disease condition is cancer.